Many sample analyzers have been developed for measuring the size of predetermined component particles in a sample such as blood, urine and the like, and analyzing the state of the particle distributions. Particularly in sample analyzers for detecting the distribution states of red blood cells, white blood cells, platelets and the like, red blood cells and platelets are measured by using an electrical resistance type measuring device since platelets have a relatively small size of 1 to 4 μm compared to the size of red blood cells which are 7 to 8 μm.
However, small size red blood cells may exist. Also, collapsed red blood cells have smaller size than usual. In those cases, red blood cells and platelets can not be reliably differentiated simply by the size.
Japanese Laid-Open Patent Publication No. 2000-275163 discloses a particle analyzer which produces highly reliable measurement results by measuring platelets by using both an electrical resistance type measuring device and an optical measuring device. This particle analyzer adopts more reliable platelet number between a platelet number by the electrical resistance type measuring device and a platelet number by the optical measuring device.
In the particle analyzer disclosed in Japanese Laid-Open Patent Publication No. 2000-275163, however, two types of measurement samples allocated from the same sample must be prepared, and the measurements are performed by the electrical resistance type measuring device and the optical type measuring device using the respective measurement samples. Disadvantages thus arise relating to the cost of the reagents used in the preparations, and the simple doubling of the number of measurement processes, which make it difficult to reduce analysis costs.